Refrigeration



.Nov'.2s,1939. v K EL Em 2,181,276

REFRIGERATI ON Filed April 12, 1937 3 Sheets-Sheet l mvrswrozgs Nov. 28.1 w. G. KOGEL- ET AL REFRIGERATION Filed April 12, 1937 s Sheets-Sheet 2INVENTORS mm" by W @WL WATTORNEY.

NOV. 28, 1939. w Cj 2.181,Z76

REFRIGERATION Filed April 12, 1937 3 Sheets-Sheet 5 39 I 2 Q @I m F j vi I 50 5/ a 'II a? a o I x 75 r a 7b 7 -36 Ill 75 Q E 5/ a0 i I I i .75-L INVENTOBS BY I (P mam ATTQRNEY.

Patented Nov. 28, 1939 UNITED STATES 2,181,276- REFRIGERATIQN WilhelmGeorg Kiigel, Paul strandbergrand Gunnar Grubb, Stockholm,Swedem'assignorsDby mesne assignments, to Servel, Inc New York,

N. Y., a corporation of Delaware Application April 12, 1932;'Sei'ia'l'No. 136,274

In Germany April 16, 1936 25 Claims. This inventionrelates torefrigeration, and

more particularly to defrosting of a cooling ele-v refrigeration systemto effect defrosting is avoided.

Another object of the invention is to utilize heat from a part of arefrigeration system toheat a cooling element thereof to cause rapidmelting of frost accumulated on the cooling element.

A furtherobject of the invention is to heat a cooling element to causemelting of frost, and to terminate such heating automatically when thecooling element is substantially defrosted.

A still further object of the invention is to provide a heating systemfor heating a cooling element which, in addition to defrostingthe\cooling element, may be effectively utilized to heat an enclosedspace in which the cooling element is arranged, so that the enclosedspace can be maintained substantially at a desired temperature.

The above and other objects and advantages of the invention will be morefully understood from the following description taken in connection withthe accompanying drawings forming a part of this specification, and ofwhich Fig. 1 diagrammatically illustratesa refrigeration system providedwith defrosting apparatus embodying the in Fig. 1; Fig. 3 is afragmentary sectional view illustrating a modification of the apparatusshown in Fig. 1 whereby, in addition to heating the cooling element, thestorage space in which 'it is arranged may be heated to maintain thelatter substantially at a desired temperature; Fig. 4 is a view inelevation of the apparatus shown in Fig. 3; Fig. 5 ma fragmentarysectional view illustrating a further modificationof the apparatus shownin Fig. 1; Fig. 6 is a sectional view on line 6-5 of Fig. 5; and Figs. 7and 8 are'fragmentary views of the apparatus shown in Fig. 5 toillustrate more clearly parts of the apparatus.

Referring to Fig. 1, the invention is shown in connection with arefrigeration system of a uniform pressure absorption type, generally asdescribed in Patent No. 1,609,334 to von Platen and Munters, in which anauxiliary pressure equalizing gas is employed. It is to be understood,however, that the invention can 'be employed with other types ofrefrigeration systems.

The system includes a cooling element or evap- Agdl. 62-5) orator l0disposed in an enclosed space H which may form a food storagecompartment of a thermally insulated refrigerator cabinet l2. Therefrigerant fluid, such as ammonia, evaporates in the evaporator Ill anddiffuses into an inert gas, 5 such as hydrogen, to produce arefrigerating effeet. The resulting gaseous mixture of refrigerant andhydrogen flows from evaporator l0 through conduit l4, gas heat exchanger[5, and conduit l1 into an absorber Hi. In absorber I8 10 therefrigerant gas is absorbed by a suitable liquid absorbent, such aswater. The inert hydrogen gas is returned to evaporator I0 throughconduit IS, the gas heat exchanger l5 and conduit 20; and the enrichedabsorption liquid is con- 15 ducted to an accumulation vessel 2|, andthence through a liquid heat exchanger 22 to generator 23. e

By heating generator 23, as by a gas burner 24, refrigerant is expelledfrom the absorption 20 liquid, liquefied in an air-cooled condenser 25,and then returned through conduit 26 to evaporator III to complete therefrigerating cycle. The weakened absorption liquid from whichrefrigerant has been expelled is conducted from 25 generator 23 through,liquid heat exchanger 22 and conduit 21 into the upper part of absorberl8. The generator 23 and liquid heat exchanger 22 may be embedded insuitable insulating material 28. A conduit 29 is connected to the lower0 part of condenser 25 and the gas circuit, as at the gas heat exchangerl5, for example, so that; any non-condensible gas which may pass intothe condenser can flow to the gas circuit and not be trapped in thecondenser. 5 In accordance with this invention the cooling element In isindependently heated to cause melting of frost that is formed thereon,so that the need for'modifying the operation of the refrigeration-system to defrost the cooling element is 40 avoided. Althoughheating of the cooling element may be effected by any suitable source ofheaa'it ispreferred to utilize heat from a part of the refrigerationsystem to heat the cooling element and thereby cause melting of frost.The

heat transfer system for transferring heat from a part of therefrigeration system, such as generator 23, for example, to coolingelement ill includesan evaporation member 30 which is in good heatexchange relation with generator 23 and embedded in the insulatingmaterial 28. The evaporation member 30 is connected at its upper end byan inclined conduit 3|, casing 32, and conduit 33 to a condenser member34 which serves as the heating element of evaporator l0. The

condenser member 34 is in the form of a looped coil which may be formedintegrally with or secured in any suitable manner to a side wall ofevaporator H). To conduct heat effectively to the inner portions of thelayer of frost heat transfer fins 34' are provided at the side ofcooling element l0.

The casing 32 is connected to the horizontal ends of conduits 3| and 33.To the lower part of casing 32 is secured an expansible bellows 35having a lower end plate 36 with which is integrally formed a piston 31.A pin 38 extending upward from piston 31 is secured to an upper endplate 39'of a second expansible bellows 43 which is smaller in diameterthan bellows 35. The bellows 40 is secured to the upper part of casing32, and, together with casing 32 and bellows 35, forms a chamber 42. Aspiral spring 43 disposed about bellows 35 is connected or secured atits upper end to casing 32 and is connected or secured at its lower endto end plate 36, so that the weight of piston 31 and pin 38 may bepartly or fully counter-balanced.

Extending upward from the upper end plate 39 is a pin 44 having anenlarged head 45 which is adapted to be engaged and held by a pair ofleaf springs 46 fixed to a pair of arms or plates 41 which are securedto casing 32. The upper end of pin 44 is connected to a wire 48 whichextends upward and is wound about and secured at its end to a pulley 49.The pulley 49 is fixed to a rod 53 which extends through the rearinsulated wall of cabinet l2 and an opening in a front plate 5| of thecooling element ID. A lever 52 is secured to the inner end of rod 50. torotate pulley 49 and thereby raise pin 44 from a lower position to theupper position shown in Fig. 2.

The evaporation member 30, chamber 42, condenser member 34, andconnecting conduits 3| and 33 form a hermetically sealed circuit adaptedto contain a suitable volatile fluid for transferring heat fromgenerator 23 to cooling element Hi. When the refrigeration system is inoperation and burner 24 is heating generator 23, liquid in evaporationmember 30 is evaporated. The vapor passes upward through conduit 3|chamber 42, and conduit 33 into condenser member 34. The vapor iscondensed in member 34 and flows downward through conduit 33 and back toevaporation member 30 where it is again When the cooling element I0 issubstantiallydefrosted, the pin 44 is below the position shown in Fig.2, with the upper end of the enlarged head 45 hearing against the lowerend of leaf springs 46. In such lower position the expansible bellows 40is contracted and bellows 35 is elongated with the piston 31 being inits lower position. With piston 31 in its lower position, a maximumquantity of liquid can be held in the lower part of chamber 42 whichconstitutes an inactive portion of the heat transfer system, and liquidcon densate formed in member 34' and flowing toward member 30 is trappedin chamber 42, The

volume of the lower part of chamber 42 is such that, when the enlargedhead 45 of pin 44 is hearing against the lower ends of leaf springs 46and 'not positively engaged and held by the latter,

the condensed vapor is trapped in chamber 42 and cannot fiow back toevaporation member 30. Under these conditions whatever liquid there isin member 30 continues to evaporate until member 30 is depleted ofliquid, and thereafter no heat is transferred from generator 23 tocooling element Hi.

When a layer of, frost has formed on cooling element I0 and it isdesired to defrost the same, lever '52 in front of cooling element In isturned in a clockwise direction whereby rod 50 and pulley 49 arerotated. This causes Wire 48 to be wound about pulley 49 and pullspin-44 upward from its lower position to its upper position shown inFig. 2. With such upward movement of pin 44, the bellows 4!! is expandedand bellows 35 is contracted. This moves piston 31 upward whereby liquidis caused to overflow from chamber 42 or'the inactive portion of thesystem into conduit 3| and fiow into evaporation member 30. The liquidis evaporated in member 30 and condensed in member 34 in the activeportion of the system, thereby giving up and rejecting heat to frostformed on the cooling element. Liquid formed in member 34 flows back tomember 30 and is again evaporated. I

When the cooling element In is substantially defrosted the pin 44 iscaused to move downward to its lower position, as will be presentlyexplained, so that condensate formed in member 34 is trapped in chamber42 and cannot flow back to evaporation member 30. The liquid in member30 continues to evaporate until this member is depleted of liquid,whereupon transfer of heat no longer takes place from generator 23 tocooling element I0. When the pin 44 is moved downward the pulley 49 iscaused to rotate in a counter-clockwise direction and lever 52 is movedback to its initial position from which it can be subsequently moved toinitiate defrosting when a layer of frost has again formed on coolingelement l0.

When the cooling element I0 is substantially defrosted and the liquid inthe heat transfer 1 system is trapped in the chamber 42 the temperatureof the cooling element and condenser member 34 is relatively low,assuming that the refrigeration system is being operated. When thecooling element is coated with a layer of frost and piston 31 is raised.to its upper position, vaporization and condensation of the volatilefiuid takes place to transfer heat from generator 23 to cooling elementl0. With heat being transferred from generator 23 to condenser member34, the temperature of the condenser member increases to such a valuethat heat is transferred to the frost and remains at such increasedtemperature until the cooling element is substantially defrosted. Whencondenser member 34 is no longer in contact with ice or frost itstemperature rises" suddenly. This temperature rise of condenser member34 after cooling element In is substantially defrosted is utilized inthe embodiment just described to terminate automatically the transfer ofheat to cooling element It), as will now be explained.

The physical characteristics of the volatile fluid selected arepreferably such that; when the condenser member 34 is at the increasedtemperature during defrosting, the pressure existing in 70 all of the"butane is trapped in chamber 42, and

in the system is substantially equal to atmospheric pressure the forcesacting on the upper and lower end plates 36 and 39 are substantially thesame and no movement of bellows 35 and 46 will tend to take place. Ifthe predetermined pressure existing in the system is slightly aboveatmospheric pressure the downward force exerted on lower end plate 36will be greater than the upward force exerted on upper end plate 39 dueto the fact that the latter is smaller in area. The greater-thispredetermined temperature is above atmospheric pressure, the greaterwill be the net downward force tending to move pin 44 out of engagementwith leaf springs 46. During this period when member 34 is in contactwith ice and frost and the heat transfer system is at the predeterminedpressure, therefore, the leaf springs 46 should be sufficiently strongto keep pin 44 and piston 31 in the upper position shown in Fig. 2.

When the cooling element is substantially defrosted and condenser member34 is no longer in contact with ice orfrost, the temperature of member34 rises suddenly. Since the temperature of member 34 is increased, thepressure in the heat transfer system increases to a value above thepressure existing when the member 34 is in contact with ice or frost.The bellows 35 and 46, pin 44 and leaf springs 46 are so arranged thatat this increased pressure the net downward force exerted on lower endplate 36, due to the greater diameter of bellows 35, is sufllcient tocause bellows 35 to move downward and move the upper end 45 of pin 44out of engagement with leaf springs 46.

The liquid condensate no-w formed in condenser member 34 is trapped inchamber 42, as explained above, and liquid cannot flow back .toevaporator member 30. When member 36 is depleted of liquid and all ofthe liquid has accumulated in chamber 42, heat transfer no longer takesplace from generator 23 to cooling element I0. When it is again desiredto initiate defrosting, lever 52 is turned to raise pin 44. so that itwill be engaged and held by leaf springs 46,

. whereby liquid flows from chamber 42 into memher 36 to again effectheating of cooling element It.

- In any case, irrespective of the volatile fluid "used, the leafsprings 46 and spiral spring 43 may be of such strength that, duringheat transfer the tension of spiral spring 43 and the frictionalengagement of leaf springs 46 and pin 44(- Among the volatile fluidsthat may be used;

for example, butane possesses such physical.

characteristics that it is particularly desirable in a system of thepresent type. If it is assumed that the refrigeration system is inoperation and the cooling element is substantially defrosted and at atemperature of about 10 C.,the pres-- sure existing in the heat transfersystem when butane is used is about .7/kg/cm It is further assumed thatsubstantially all of the air has been removed from the heat transfersystem before it is'charged with butane. Under these conditions thepressure in the system is below atmospheric pressure. If lower end plate36 is one square cm. greater in area than upper end plate 39 theresultant force acting upward on lower end plate end plate for anexpansible bellows 62.

36 is about 0.3 kg. greater than that acting downward on upper end plate39. The greater force on lower end plate'36 tends to move pin 44 intoengagement with leaf springs 46, and the latter must be of such strengththat the elongated head 45 cannot pass upward between the lower ends ofthe springs.

When cooling element It) is coated with a layer 'of frost and piston 31is moved to its upper position by turning lever 52, evaporation andcondensation of butane takes place to cause melting of frost. Thetemperature of condenser member 34 is now increased to a valuesufficient for heat transfer to the frost, as explained above, and thepressure of butane in the heat transfer system for this temperature isabout 1.0 kg/cm and substantially equal to atmospheric pressure. Due to,the fact that the pressures within and outside the system aresubstantially equal no displacement or movement of the bellows 35 and 40takes place. When member 34 is no longer in contact with ice or frost,however, and it is assumed that the temperature of condenser member 34further-increases to about +10 C.,

the pressure of butane in the system is about 1.5

by chamber 42 will be sufficiently large to trap liquid butane andprevent butane from flowing back to the evaporation member 36. The leafsprings 46 in any particular .case may be so shaped that a greater forceis required to move pin 44 in one direction than in the other direction.a

It will now be understood that heat may be supplied to-cooling elementill to effect defrosting without disturbing the operation of ,therefrigeration system. With such an arrangement it is not necessary tosuspend or reduce the refrigerating effectproduced by cooling element l0during a defrosting period. Ffurther, defrosting can be effected veryrapidly because heat is conducted directly to the cooling element, the

heat transfer system preferably being so constructed and arranged that arapidrate of. heattransfer is effected.

In addition to supplying heat to cooling element l0 to effectdefrosting, the heat transfer system also may be arranged to supply heatto the thermally insulated space H to maintain the latter substantiallyat a desired temperature. This is particularly desirable "when thesource of heat is more or less diflicult to regulate. Such amodification of the embodiment just described is illustrated in Figs. 3and 4 with parts similar to those shown in Figs. 1 and 2 indicated bythe same reference numerals.

In Figs. Sand 4 the upper ends of a U-shaped bracket 66 are secured tothe casing 32. The lower part 61' of bracket 60 serves as an upper Thebe lows 62 is providedwith a lower end plate 63 which is fixed to thelower part of a rectangular frame 64. The frame 64 is at right angles tobracket 66 and is secured at its upperpart to lower end plate 36 ofbellows 35. A spiral spring 65 is interposed between the upper part offrame 64 and lower part of bracket 60. To the lower end plate 63isconnected one end .of a flexible in chamber 42.

tube 66 which is connected at its other end to a thermal bulb 6I locatedin the thermally insulated space I The bellows 62, tube 66, and bulb 61constitute an expansible fluid thermostat containing a volatile fluidwhich increases and decreases in volume with corresponding changes oftemperature.

When-the storage space H is at the desired temperature, piston 31 is inits lower position and the liquid in the heat transfer system is heldWhen the temperature of storage space H falls below the desired value,however, the volatile fluid in the expansible fluid thermostat becomesreduced in volume whereby expansible bellows 62 contracts. Since theupper end plate 6| of bellows 62 is immovable due to the fact that it isfixed to the lower part of bracket 68, the contraction of bellows 62will I cause its lower end plate 63 to move upward.

movement of lower end plate 36, whereby bellows 35 is contracted andpiston 3! is raised. Raising of piston 3! causes liquid to-overflow fromchamber 42 and pass into evaporation member 38. With liquid in member 38the transfer of heat takes place from generator 23 to cooling elementI0, thereby raising the temperature of storage space II.

. When the storage space tends to rise above the predeterminedtemperature, the volatile fluid in the expansible fluid thermostatincreases in volume to cause the lower end plate 63 to move downward andcarry with it the frame 64. Downward movement of frame 64 lowers endplate 36 of bellows 35 whereby the latter is expanded and piston 31 islowered, thereby trapping liquid condensate in chamber 42 and preventingflow thereof into evaporation member 38. When member is depleted ofliquid, transfer of heat from generator 23 to storage space II no longertakes place.

Instead of automatically terminating the sup- .ply of heat to coolingelement In in accordance with an increase in pressure in the-heattransfer system, a control mechanism may be provided whereby defrostingis terminated in accordance I III which is arranged during defrosting tocontact a layer of frost II formed on cooling element In. 'The arm I8may be formed integrally with an arcuate-shaped plate I2 having one partI3 of greater radius than another part I4. The plate I2 is eccentricallypivoted at 75 to a disk I6 which is secured to a pin 11. The pin 11 isjournaled in the forked arms I8 of a depending bracket I9 which issecured at its upper end to a casing 80. The casing 88 serves as ahousing for the expansible'bellows and is provided with an opening atits lower end through which extends a contact member'8l secured to lowerend plate 36. The contact member 8| "is arranged 82 having-a shorthorizontal arm on which is mounted a pin 83. The pin 8 3.is urged orbiased upward by a spring 84 and is-adapted to fit into a recess 85 indisk I6 to prevent rotation of the latter.

To the lower end plate 36 of bellows A coil spring 86, which is disposedabout an enlarged end of pin 11, is connected at one end to disk I6 andat its other end to one of the arms I8 of bracket I9. The spring 86 isso arranged about pin 11 that it is effective to move disk I6 in aclockwise direction when pin 83 is moved downward and out of recess 85.A crank 81 is secured to pin H for turning disk I6. To keep arm I0bearing against the layer of frost II during defrosting, the plate iscaused'to move in a counter-clockwise direction by a coil spring 88having one end connected to plate I2 and the other end connected tobracket I9.

When it is desired to initiate defrosting the parts of the controlmechanism are moved into the position shown in Fig. 5, as will bepresently explained. In' this position the piston 31 is in its upperposition and liquid overflows from chamber 42 into evaporation member38, whereupon transfer of heat to cooling element I8 takes place. As thefrost on cooling element I8 melts and decreases in thickness, coilspring 88 is mo-ving plate I2 in a counter-clockwise direction so thatthe erid of arm III is constantly contacting the melting frost. Thiscounter-clockwise movement of plate I2 continues until the part I4thereof moves under the projecting member 8|, whereupon the lattersuddenly moves downward from part I3 to part I4 due to the tension ofcoil spring 43. When this occurs the cooling element is substantiallydefrosted and plate I2 has turned in a counter-clockwise direction sucha distance that the end of arm I0 is contacting a side of coolingelement I 0. The downward move- -ment of projecting member 8| movespiston 31 evaporation member 30, whereupon transfer of heat to coolingelement I8 no longer takes place.

When projecting member 8| moves downward bracket 82 is also moveddownward whereby pin 83 moves out of recess 85 in disk I6. With pin 83no longer locking disk I6 in position, the coil spring 86 is effectivetorotate disk I6 in a clockwise direction to the position shown in Fig.8.

.The parts of the control mechanism are so proportioned and arrangedthat arm I6 is moved away from the cooling element III a considerabledistance 'so that there will be no danger of. the contactarm' freezingfast to the layer of frost that. is subsequently formed on the coolingelement. Withsuch counter-clockwise movement of disk I6 the plate I2,due to the fact that it is eccentrically pivoted on/disk I6, can movedownward a suflicient distance to assume the position shown in Fig. 8with part I3 directly beneath the downward projecting member 8|.

When it is again desired to initiate defrosting of cooling element I0,crank 81 is turned in a counter-clockwise direction to put spring 86under tension and also locate recess 85 directly above thelocking pin83. The bracket 82 is then moved upward so that pin 83 will lock disk 16in position and also force projecting member 8| vupward, whereuponpiston 3! is raised and liquid will overflow into evaporation member 38.When bracket 82 is moved from the lower position shownlin Fig. 8 to theupper position shown in Fig. 6, contact arm I0 is again brought intocontact with the layer of frost and spring 88 is put under tension toeffect counter-clockwise movement of plate I2 as frost melts and becomessmaller and smaller in thickness on cooling element l8.

Although several embodiments of the invention have been shown anddescribed, it will be apparent to those skilled in the art that variousmodifications and changes may be made without departing from the spiritand scope of the in- .vention. It is therefore contemplated to cover allmodifications and changes which come within the spirit of the invention,as pointed out in the following claims.

What is claimed is:

1. Apparatus for defrosting a cooling element of a refrigeration systemand including a flrst member associated with a source of heat andanother member in thermal relation with the cooling element, meansconnecting said members to form a closed circuit containing a volatilefluid, said circuit having an active portion in which fluid is adaptedto circulate to transfer heat from the source of heat to the coolingelement and an inactive portion adapted to contain fluid in a liquidstate, and means responsive to the pressure existing in said circuit forcontrolling the quantity of liquid in saidactive portion to control thetransfer of heat from the source of heat to the cooling element. 1

2. Apparatus for defrosting a cooling element of a refrigeration systemand including a first member associated with a source of heat andanother member in thermal relation with the cooling element, meansconnecting said members to form a closed circuit containing a volatilefluid, said circuit having an activeportion in which fluid is adapted tocirculate to transfer heat from the source of heat to the coolingelement and an inactive portion adapted to contain fluid in a liquidstate, and means including a movable member adapted during heat transferto said cooling element to bear againstfa diminishing layer of meltingfrost on said cooling element for controlling the quantity ofliquid insaid active portion to control the transfer of heat from the heat sourceto the cooling element. Y

3. Apparatus as defined in claim 2, in which said means for controllingthe quantity of liquid in said active portion is so constructed andarranged that said movable member is moved away from the surface of thecooling element when the transfer of heat no longer takes place, so'thatsaid movable member will not freeze fast to said cooling element.

4. Apparatus'for defrosting p cooling element of a refrigeration systemand comprising a first -member associated with a source of heat and asecond member in thermal relation with the c ooling element, meansconnecting said members to form a closed circuit containing a volatilefluid, said circuit having an active portion in which fluid is adaptedto circulate to transfer heat from the heat source to the coolingelement and an inactive portion adapted ,to contain fluid in a liquid offrost formed on the latter, said last-mentioned means being soconstructed and arranged that, when said second member is no longer incontact with ice or frost and the pressure in the circuit increases,substantially all of the fluid in the circuit is trapped in saidinactive portion whereby transfer of heat no longer takesplace from theheat source to said cooling element.- 5. In a method of refrigerationattended by formation of frost or ice, that improvement which consistsin melting said frost or ice by conducting heat thereto in a fluidmedium, and controlling flow of said medium by pressure of the medium.

6. A method asset forth in claim 5 in which said fluid undergoesvaporization and condensation.

7. A method as set forth in claim 5in which said fluid is circulatedbetween a place of vaporization and a place of oondensatiom'the latterbeing in heat transfer relation with the frost or ice, and condensate iswithheld from said place of vaporization by increase in pressure of thevapor.

8. In a refrigerator having a cooling surface subject to' formation of"frost or ice, a fluid heat transfer circuit having a portion inheatexchange relation with said cooling surface for melting said frostor ice, and means for controlling flow of fluid in said circuitresponsive to pressure in the circuit.

9. A refrigeratorfas set forth in claim 8 in which the fluid in saidcircuit undergoes vaporization and condensation, and said control meanscauses withholding of condensate from the place of vaporizationresponsive to increase in pressure.

10. In a refrigeration system including a cooling element subject toformation of frost orice thereon, means for supplying hot gaseous fluidto melt said frost or ice, and means to control the supply of said fluidresponsive to the pressure thereof.

ll. Refrigeration apparatus having a" high temperature part and a lowtemperature part, the latter being subject to formation'of frost or icethereon, means forming a path, for flow of fluid for conducting heatfrom said high temperature part to said low temperature part forcausingmelting of said frost or ice, and means for 13. The combination with arefrigeration system having a' cooling element subject to' formation offrost or ice, of means for transferring heat to said frost or ice at 'atemperature and rate to cause meltings thereof, and fluid pressureoperated means for controlling said heat transfer means.

14. In refrigeration apparatus having a thermally insulated space nd acooling element arranged to cool said sp ce and subject to formation offrost or ice, a first member associated with a source of heat andanother memberassociated with said cooling element, conduit meansconholding substantially all of the liquid fluid in the circuit andbeing arranged to receive liquid from said othermember, and meansincluding a control element responsive to a temperature conditionaffected by said cooling element for causing liquid to flow from saidsecond portion into said first portion whereby transfer of heat takesplace from said heat source to said cooling element.

' 15. An absorption refrigeration system having a high temperature placeof heating where vapors are generated and a low temperature place whereheat is abstracted by evaporation of liquid to produce a refrigeratingeffect, the place of heat abstraction being subject to. formation offrost or ice, structure providing several paths of flow for fluid fromthe place of'heating to the place of heat abstraction, one of the pathsof flow including a portion in which vaporous fluid from the place ofheating is condensed to liquid and from which liquid flows to the placeof heat abstraction for evaporation therein, another of the paths offlow being controllable to supply vaporousfluid from the place ofheating to the place of heat abstraction when desired, the heat fromvaporous fluid at the place of heat abstraction being absorbed by thefrost or ice .so that heat is transferred to the frost or ice at atemperature above the melting point thereof and at a rate sufficient tocause melting of the frost or ice. I

16. An absorption refrigeration system having a high temperature placeof heating where vapors are generated and a low temperature place whereheat is abstracted by evaporation of liquid to produce a refrigeratingeffect, the place of heat abstraction being subject to formation offrost or ice, structure providing several paths of flow for fluid fromthe place of heating to the place of heat abstraction, one of the pathsof flow including a portion in which vaporous fluid from the pace ofheating is condensed to liquid and from which liquid flows to the placeof heat abstraction for evaporation therein, another of the paths offlow being adapted to supply vaporous fluid from the place of heating tothe place of heat abstraction, the heat from vaporous fluid at the placeof heat abstraction being absorbed by the frost or ice so that heat istransferred to the frost or ice at a temperature above the melting pointthereof and at a rate sufficient to cause melting of the frost or ice,and means controlling the supply {of vaporous fluid to the place of heatabstracion.

1'7. An absorption refrigeration system having a high temperature placeof heating where vapors are generated and a low temperature place whereheat is abstracted by evaporation of liquid to produce a refrigeratingeffect, the place of heat abstraction being subject to formation offrost or ice, structure providing several paths of flow for fluid fromthe place of heating to the place of heat abstraction, one of the pathsof flow ineluding a portion inwhich vaporous fluid from the place ofheating is condensed to liquid and from which liquid flows to the placeof heat abstraction for evaporation therein, another of the paths offlow being adapted to supply vaporous fluid from the place of heating tothe place of heat abstraction, the heat from vaporous fluid at the placeof heat abstraction being absorbed by the frost or ice so that heat istransferred to the frost or ice at a temperature above the melting pointthereof and at a'rate suflicient to cause melting of the frost or ice,and means responsive to a condition representing substantially adefrosted state of the place of heat abstraction-to stop flow ofvaporous fluid to the place of heat abstraction. 18. In the art ofrefrigeration with an'absorptlon refrigerating system includingvaporizing fluid at a place of vapor expulsion, condensing the vaporizedfluid to liquid at a place of c'ondensation, and flowing liquid from theplace of condensation to a place of vaporization for vaporizationtherein to produce a refrigerating eflect,

the place of vaporization being subject to formation of frost or ice,the improvement which consists in addition in vaporizing liquid andflowing the vapors to the place of. vaporization, the heat from thevapors being absorbed by the frost or ice so that heat is transferred tothe frost or ice at a temperature above'the melting point thereof and ata rate sufficient to cause melting of the frost or ice.

sorbed by the frost or ice so that heat is trans- I ferred to. the frostor ice at a temperature above the melting point thereof and at a ratesufficient to cause melting of the frost or ice, and controlling theheating of liquid to control flow of vaporous fluid to the place ofvaporization.

20. In the art of refrigeration with an absorption refrigerating systemincluding 4 vaporizing fluid at a place of vapor expulsion, condensingthe vaporized fluid to liquid at a place of condensation, and flowingliquid from the place of condensation to a place of vaporization forvaporization therein to produce a refrigerating eifect, the. place ofvaporization being subject to formation of frost or ice, the improvementwhich consists in addition in flowing vaporized fluid to the place .ofvaporization, the heat from' the vaporized fluid being absorbed by thefrost or ice so that heat is transferred to the frost or ice at atemperature above the melting point thereof and at a rate suflicient tocause melting of the frost or ice, accumulating liquid at a place ofaccumulation in the path of flow of the vaporized fluid to stop flow ofthe vaporized fluid to the place of vaporization, and removing liquidfrom the place of accumulation to permit flow of vaporized fluid to theplace of vaporization.

21. In the art of refrigeration with an absorption refrigerating systemincluding vaporizing fluid at ya place of vapor expulsion, condensingthe'vaporized fluid to liquid at a place of condensation, and flowing,liquid from the place of condensation to a place of vaporization forvaporization therein to produce a refrigerating effect, the place'ofvaporization being subject to formation 'of frost-or ice, theimprovement which consists in addition in vaporizing liquid to formvapors, flowing'the vapors to the place of vaporization, and condensingthe vapors by absorption of heat by the frost or ice, so that heat istransferred to the frost or ice .at a temperature above the meltingpoint thereof and at a rate suflicient to cause melting 'of the frost orice.

22. An absorption refrigeration system having a high temperature placeof heating where vapors are generated and a low temperature place whereheat is abstracted by evaporation of liquid to produce a refrigeratingeffect, the place of heat abstraction being subject to formation offrost or ice, structure providing several ,paths of flow for fluid fromthe place of heating to the place of heat abstraction, one of the pathsof flow including a portion in which vaporous fluid from the place ofheating is condensed to liquid and from which liquid flows to the placeof heat abstraction for evaporation therein, another of the paths offlow being adapted to supply vaporous fluid from the place of heating tothe place of heat abstraction, the heat from vaporous fluid at the placeof heat abstraction being absorbed by the frost or ice so that heat istransferred to the frost or ice at a temperature above the melting pointthereof and at a rate sufficient to cause melting of the frost or ice, aliquid trap in said other path of flow operative to stop the supply ofvaporous fluid to'the place of heat abstraction, and means to removeliquid from said trap to cause vaporous fluid to be supplied to theplace of heat abstraction.

23. An absorption refrigeration system having a high temperature placeof heating where vapors are generated and a low temperature place whereheat is abstracted by evaporation of liquid to produce a refrigeratingeffect, the place of heat abstraction being subject to formation offrost or ice, structure providing several paths of flow for fluid fromthe place of heating to the place of heat abstraction, one of the pathsof flow including a portion in which vaporous fluid from the place ofheating is condensed to liquid and from which liquid flows to the placeof heat abstraction for evaporation therein, another of the paths offlow being controllable to supply vaporous fluid from the place ofheating to the place of heat abstraction when desired, the vaporousfluid supplied to the place of heat abstraction being condensed byabsorption of heat by the frost or ice so that heat is transferred tothe frost or ice at a temperature above the melting point thereof and ata rate suflicient to cause melting of the frost or ice.

24. In a refrigerator having a cooling surface subject to formation offrost or ice, a fluid heat transfer circuit in which a heated fluid isadapted to flow and having a portion in heat exchange relation with saidcooling surface, the heat from fluid in said portion being absorbed bythe frost or ice, so that heat is transferred to the frost or ice at atemperature above the melting point thereof and at a rate suflicient tocause melting of the frost or ice, and means including a movable memberadapted during heat transfer to the frost or ice to contact a.diminishing layer of melting frost or ice on said cooling surface tocontrol flow of heated fluid in said circuit.

25. The combination as set forth in claim 24 in which said means forcontrolling flow of heated fluid in said heat transfer circuit is soconstructed and arranged that said movable member is moved away from thesurface of said cooling element when heated fluid no longer flows insaid circuit to said portion, so that said movable member will notfreeze fast to said cooling surface.

WILHELM GEORG KGGEL. PAUL STRANDBERG. GUNNAR GRUBB.

